Pilot transmission in a wireless communication system

ABSTRACT

Techniques for transmitting pilot and traffic data are described. In one aspect, a terminal may scramble its pilot with a scrambling sequence generated based on a set of static and dynamic parameters. The static parameter(s) have fixed value for an entire communication session for the terminal. The dynamic parameter(s) have variable value during the communication session. The terminal may generate a scrambling sequence by hashing the set of parameters to obtain a seed and initializing a PN generator with the seed. The terminal may then generate the pilot based on the scrambling sequence. In another aspect, the terminal may use different scrambling sequences for pilot and traffic data. A first scrambling sequence may be generated based on a first set of parameters and used to generate the pilot. A second scrambling sequence may be generated based on a second set of parameters and used to scramble traffic data.

The present application claims priority to provisional U.S. ApplicationSer. No. 60/883,758, entitled “WIRELESS COMMUNICATION SYSTEM,” filedJan. 5, 2007, provisional U.S. Application Ser. No. 60/883,870, entitled“PILOT SIGNAL TRANSMISSION FOR A WIRELESS COMMUNICATION SYSTEM,” filedJan. 8, 2007, and provisional U.S. Application Ser. No. 60/883,982,entitled “PILOT SIGNAL TRANSMISSION FOR A WIRELESS COMMUNICATIONSYSTEM,” filed Jan. 8, 2007, all assigned to the assignee hereof andincorporated herein by reference.

BACKGROUND

I. Field

The present disclosure relates generally to communication, and morespecifically to techniques for transmitting pilot in a wirelesscommunication system.

II. Background

Wireless communication systems are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, etc. These wireless systems may be multiple-access systemscapable of supporting multiple users by sharing the available systemresources. Examples of such multiple-access systems include CodeDivision Multiple Access (CDMA) systems, Time Division Multiple Access(TDMA) systems, Frequency Division Multiple Access (FDMA) systems,Orthogonal FDMA (OFDMA) systems, and Single-Carrier FDMA (SC-FDMA)systems.

A wireless communication system may include many base stations that cansupport communication for many terminals on the forward and reverselinks. The forward link (or downlink) refers to the communication linkfrom the base stations to the terminals, and the reverse link (oruplink) refers to the communication link from the terminals to the basestations. The terminals may be located anywhere within the system, andeach terminal may be within the coverage of zero, one, or multiple basestations at any given moment. A terminal may transmit a pilot on thereverse link to allow the base stations to detect the terminal. Thepilot may also be used to estimate the channel conditions for theterminal, to assign the terminal to an appropriate base station that canefficiently serve the terminal, and/or for other purposes. The pilottransmitted by the terminal, although useful, represents overhead.

There is therefore a need in the art for techniques to efficientlytransmit pilot on the reverse link.

SUMMARY

Techniques for transmitting pilot and traffic data by a terminal on thereverse link are described herein. In one aspect, the terminal mayscramble its pilot with a scrambling sequence generated based on a setof parameters, which may include at least one static parameter andpossibly at least one dynamic parameter. The at least one staticparameter may have fixed value for an entire communication session forthe terminal, may be determined during initial system access by theterminal, and may be independent of a serving sector for the terminal.The at least one dynamic parameter may have variable value during thecommunication session and may include a parameter for system time. Ascrambling sequence may be generated based on the set of parameters,e.g., by hashing the set of parameters to obtain a seed and theninitializing a pseudo-random number (PN) generator with the seed. Apilot may then be generated based on the scrambling sequence, e.g., byscrambling pilot data with the scrambling sequence to obtain scrambledpilot data and then generating pilot symbols based on the scrambledpilot data.

In another aspect, the terminal may use different scrambling sequencesfor pilot and traffic data. A first scrambling sequence may be generatedbased on a first set of parameters. A pilot may be generated based onthe first scrambling sequence and may be sent to at least one sectorincluding the serving sector. A second scrambling sequence may begenerated based on a second set of parameters. Traffic data may bescrambled based on the second scrambling sequence to obtain scrambledtraffic data, which may be sent to the serving sector. The first set mayinclude at least one parameter independent of the serving sector. Thesecond set may include at least one parameter dependent on the servingsector. The first and second sets may each include a dynamic parameter,e.g., a parameter for system time.

Various aspects and features of the disclosure are described in furtherdetail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system.

FIG. 2 shows a superframe structure for the reverse link.

FIG. 3 shows a block diagram of a terminal and two sectors/basestations.

FIG. 4 shows a block diagram of a transmit processor.

FIG. 5 shows a block diagram of a transmit (TX) pilot processor.

FIG. 6 shows a block diagram of a receive processor.

FIG. 7 shows a process for transmitting pilot by the terminal.

FIG. 8 shows an apparatus for transmitting pilot.

FIG. 9 shows a process for receiving pilot by a sector/base station.

FIG. 10 shows an apparatus for receiving pilot.

FIG. 11 shows a process for transmitting pilot and traffic data by theterminal.

FIG. 12 shows an apparatus for transmitting pilot and traffic data.

FIG. 13 shows a process for receiving pilot and traffic data by asector.

FIG. 14 shows an apparatus for receiving pilot and traffic data.

DETAILED DESCRIPTION

FIG. 1 shows a wireless communication system 100 with multiple basestations. A wireless system may also be referred to as an access network(AN). The terms “system” and “network” are often used interchangeably.For simplicity, only three base stations 110, 112 and 114 are shown inFIG. 1. A base station is a station that communicates with theterminals. A base station may also be referred to as an access point(AP), a Node B, an evolved Node B, etc. Each base station providescommunication coverage for a particular geographic area. The term “cell”can refer to a base station and/or its coverage area depending on thecontext in which the term is used. To improve system capacity, a basestation coverage area may be partitioned into multiple (e.g., three)smaller areas. Each smaller area may be served by a respective basestation subsystem. The term “sector” can refer to the smallest coveragearea of a base station and/or a base station subsystem serving thiscoverage area. The techniques described herein may be used for a systemwith sectorized cells as well as a system with un-sectorized cells. Forclarity, the techniques are described below for a system with sectorizedcells. In the following description, the terms “sector” and “basestation” are used interchangeably. Base stations 110, 112 and 114correspond to sectors A, B and C, respectively.

For a centralized architecture, a system controller 130 may couple tothe base stations and provide coordination and control for these basestations. System controller 130 may be a single network entity or acollection of network entities. For a distributed architecture, the basestations may communicate with one another as needed.

A terminal 120 may be located anywhere within the system and may bestationary or mobile. Terminal 120 may also be referred to as an accessterminal (AT), a mobile station, a user equipment, a subscriber unit, astation, etc. Terminal 120 may be a cellular phone, a personal digitalassistant (PDA), a wireless communication device, a wireless modem, ahandheld device, a laptop computer, a cordless phone, etc. Terminal 120may communicate with zero, one, or multiple sectors on the forwardand/or reverse link at any given moment. Terminal 120 may have a servingsector designated to serve the terminal on the forward and/or reverselink. Terminal 120 may also have an active set containing sectors thatmight be able to serve the terminal. In the example shown in FIG. 1,sector A is the serving sector for terminal 120, and sectors B and C arein the active set of terminal 120.

The techniques described herein may be used for various wirelesscommunication systems such as CDMA, TDMA, FDMA, OFDMA and SC-FDMAsystems. A CDMA system may implement a radio technology such ascdma2000, Universal Terrestrial Radio Access (UTRA), etc. An OFDMAsystem may implement a radio technology such as Ultra Mobile Broadband(UMB), Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20,Flash-OFDM®, etc. UTRA and E-UTRA are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). cdma2000and UMB are described in documents from an organization named “3rdGeneration Partnership Project 2” (3GPP2). These various radiotechnologies and standards are known in the art.

For clarity, certain aspects of the techniques are described below forUMB, and UMB terminology is used in much of the description below. UMButilizes a combination of orthogonal frequency division multiplexing(OFDM) and code division multiplexing (CDM). UMB is described in 3GPP2C.S0084-001, entitled “Physical Layer for Ultra Mobile Broadband (UMB)Air Interface Specification,” and 3GPP2 C.S0084-002, entitled “MediumAccess Control Layer For Ultra Mobile Broadband (UMB) Air InterfaceSpecification,” both dated August 2007 and publicly available.

FIG. 2 shows a design of a superframe structure 200 that may be used forthe reverse link. The transmission timeline may be partitioned intounits of superframes. Each superframe may span a particular timeduration, which may be fixed or configurable. Each superframe may bepartitioned into F physical layer (PHY) frames, where in general F≧1. Inone design, F=25, and the 25 PHY frames in each superframe are assignedindices of 0 through 24. Each PHY frame may cover N OFDM symbol periods,where in general N>1 and in one design N=8.

FIG. 2 also shows a subcarrier structure. The system bandwidth may bepartitioned into multiple (K) orthogonal subcarriers, which may also bereferred to as tones, bins, etc. The spacing between adjacentsubcarriers may be fixed, and the number of subcarriers may be dependenton the system bandwidth. For example, there may be 128, 256, 512, 1024or 2048 subcarriers for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz,respectively.

FIG. 2 also shows a design of a CDMA segment that can supporttransmission of pilot, signaling, and some traffic data on the reverselink. The CDMA segment may support various channels such as, e.g., aReverse Pilot Channel (R-PICH), a Reverse CDMA Dedicated Control Channel(R-CDCCH), a Reverse Access Channel (R-ACH), a Reverse CDMA Data Channel(R-CDCH), etc.

The CDMA segment may occupy a block of time frequency resources that maybe of any dimension. In one design, the CDMA segment includes S CDMAsubsegments, where in general S>1. Each CDMA subsegment may cover Mcontiguous subcarriers in N OFDM symbol periods and may include L=M Ntransmission units. A transmission unit may correspond to one subcarrierin one OFDM symbol period. In one design, each CDMA subsegment covers128 contiguous subcarriers in 8 OFDM symbol periods of one PHY frame andincludes 1024 transmission units. The CDMA segment and subsegment mayalso have other sizes.

In the design shown in FIG. 2, the CDMA segment is sent in every Q PHYframes, where in general Q>1 and as some examples Q=4, 6, 8, etc. TheCDMA segment may hop across the system bandwidth from CDMA frame to CDMAframe (as shown in FIG. 2) or may be sent on a fixed set of subcarriers(not shown in FIG. 2). A CDMA frame is a PHY frame in which the CDMAsegment is sent. In general, the CDMA segment may be sent at any rateand in a time frequency block of any dimension. Multiple terminals mayshare the CDMA segment for pilot, signaling, etc. This may be moreefficient than assigning dedicated time frequency resources to eachterminal for sending pilot and signaling on the reverse link.

In an aspect, terminal 120 may transmit a pilot on the reverse link suchthat the pilot can be received by all sectors designated to receive thepilot, e.g., all sectors in the active set of terminal 120. In onedesign, this may be achieved by scrambling the pilot with a scramblingsequence that is known by all designated sectors. Terminal 120 mayscramble the pilot such that the pilot is unique for terminal 120 amongthe pilots of all terminals in a given sector. This would then allow thesector to receive and identify the pilot from terminal 120. Furthermore,terminal 120 may scramble the pilot such that the pilot is not specificto any sector. This would then allow the pilot from terminal 120 to bereceived by all designated sectors. This would also allow terminal 120to transmit the same pilot even when terminal 120 moves about the systemand is handed off from sector to sector.

In one design, the scrambling sequence for the pilot may be generatedbased on a set of parameters that may be used to identify terminal 120and/or to minimize collision with other terminals. In general, any setof parameters may be used to generate the scrambling sequence for thepilot. The set may include only static parameters, or only dynamicparameters, or both static and dynamic parameters. A static parameter isa parameter whose value does not change during a communication sessionfor a terminal, even if the terminal is handed off from sector tosector. A static parameter may also be referred to as a sessionparameter and may be part of session state information for the terminal.A dynamic parameter is a parameter whose value can change during acommunication session.

In one design, the set of parameters for the scrambling sequence for thepilot may include the parameters given in Table 1.

TABLE 1 Parameters for scrambling sequence for pilot Parameter LengthDescription PilotID 10 bits Identifier (ID) of a sector via whichterminal 120 initially accessed the system. MACID 11 bits ID assigned toterminal 120 by the initial accessed sector. AccessSequenceID 10 bitsIndex of an access sequence sent by terminal 120 for the initial systemaccess. Access time 18 bits Time of initial system access by terminal120. System time 15 bits Time at which the pilot is transmitted byterminal 120.

The PilotID may also be referred to as, or may comprise, a sector ID, aPilotPN, etc. Each sector may transmit a pilot on the forward link andmay scramble this pilot with a scrambling sequence assigned to thatsector. The PilotPN may be an index for the scrambling sequence used bythe sector. Other forms of sector ID may also be used for the set ofparameters for the scrambling sequence for the pilot.

The Medium Access Control ID (MACID) may also be referred to as, or maycomprise, a terminal ID, a Radio Network Temporary Identifier (RNTI),etc. Each sector may assign a unique MACID to each terminalcommunicating with that sector. Each terminal may then be uniquelyidentified by its assigned MACID for communication with the sector.Terminal 120 may be assigned a MACID by a given sector upon accessingthe sector, upon being handed off to the sector, upon adding the sectorto the active set, etc. Terminal 120 may use the assigned MACID for theduration of time in which terminal 120 is in communication with thesector. The assigned MACID may be de-assigned when terminal 120 leavesthe sector, when the sector is removed from the active set, etc. TheMACID assigned by the initial accessed sector may not be valid forcommunication with other sectors but may nevertheless be used toidentify the pilot from terminal 120. Other forms of terminal ID mayalso be used for the set of parameters for the scrambling sequence.

The access sequence index may be used to identify terminal 120 for theinitial system access, before a MACID is assigned to terminal 120.Terminal 120 may randomly select the access sequence index and may sendthe corresponding access sequence on the R-ACH to access the system. Theaccess sequence may also be referred to as an access signature, anaccess probe, a random access probe, a signature sequence, etc.

The access time may be defined in various manners. For example, theaccess time may be the time at which terminal 120 sends the accesssequence on the reverse link, the time at which a sector sends an accessgrant to terminal 120 on the forward link, etc. The access time may alsobe given in various formats. In one design, the access time may be givenby a particular number of least significant bits (e.g., 18 LSBs) of aframe index for the time of initial system access by terminal 120. Inanother design, the access time may be given by a particular number ofLSBs (e.g., 9 LSBs) of a superframe index and a frame index (e.g., 5 or6 bits) of a frame within a superframe when the initial system accessoccurred.

The system time may be the time of transmission and may also be referredto as current time, current system time, transmission time, etc. Thesystem time may be given in various formats. In one design, the systemtime may be given by a particular number of LSBs (e.g., 9 LSBs) of asuperframe index and a frame index (e.g., 6 bits) of a frame within asuperframe when the transmission occurs. The system time may also begiven in other formats.

In the design shown in Table 1, the PilotID, the MACID, theAccessSequenceID, and the access time may be static parameters, and thesystem time may be a dynamic parameter. The static parameters may beobtained during initial system access and may be available at both theterminal and the accessed sector right after the initial system accessis complete. Thus, transmission and reception of pilot may commence assoon as the initial system access is complete, and does not require anyadditional messaging or configuration or any exchange of data packets.The static parameters may also be obtained during call setup, handoff,etc. The set of static parameters in Table 1 may result in highlikelihood of uniqueness of pilot scrambling among different terminalsand may reduce the likelihood of collisions among different terminals.

Table 1 shows an example set of parameters and an example size for eachparameter, in accordance with one specific design. The parameters inTable 1 may have other sizes. Other static and/or dynamic parameters mayalso be used to generate the scrambling sequence for the pilot. Forexample, the R-PICH or CDMA subsegment may hop across the systembandwidth based on a hopping pattern, and a dynamic parameter may bedefined based on the frequency resources used for the R-PICH or CDMAsubsegment.

Other combinations of parameters may also be used to generate thescrambling sequence for the pilot. For example, the scrambling sequencemay be generated based on (i) a combination of PilotID, MACID, andsystem time, (ii) a combination of MACID, access time, and system time,or (iii) some other combination of parameters. In another design, thescrambling sequence may be generated based on a static value (e.g., apseudo-random value) assigned by the initial accessed sector or selectedby terminal 120 and the system time.

The static parameters may be provided to each sector designated toreceive the pilot from terminal 120, e.g., each new sector added to theactive set of terminal 120. Other session state information may also becommunicated to the new sector upon being added to the active set. Thedynamic parameter(s) may be known to each sector and may not have to besent to the new sector.

The set of parameters used to generate the scrambling sequence for thepilot should uniquely identify terminal 120 with sufficiently highprobability. This may ensure that the likelihood of the pilots from twoterminals using the same scrambling sequence and colliding isnegligible. The desired probability of uniqueness may be achieved byusing a sufficient number of parameters with a sufficient number ofbits. In general, any set of parameters may be used to uniquely identifyterminal 120 with sufficiently high probability. The set of parametersmay be made available to all designated sectors so that these sectorscan receive the pilot from terminal 120. The set of parameters may besent via a backhaul to each new sector or via signaling from terminal120 to each new sector.

The scrambling sequence for the pilot may be generated based on the setof parameters in various manners. In one design, the set of parametersmay be used directly as a seed for a PN generator, which may implement aparticular generator polynomial. In another design, the set ofparameters may be hashed with a hash function to obtain a seed for thePN generator. The hash function may map the set of parameters to apseudo-random seed and may provide the seed with fewer bits than the setof parameters.

In one design, the set of parameters includes the PilotID (e.g., 10bits), the MACID (e.g., 11 bits), the access sequence index (e.g., 10bits), the access time (e.g., 18 bits), and the system time (e.g., 15bits). This set of parameters may be hashed to obtain a fixed-size seed(e.g., 20 bits). Other combinations of parameters and/or parameter sizesmay also be used to generate the seed, which may also have other sizes.The size of the seed may be selected based on the desired probability ofcollision between different terminals. For a 20-bit seed, theprobability of two terminals having the same seed is equal to 2⁻²⁰,which is approximately 10⁻⁶. If there are 1000 terminals in one sector,then the probability of the scrambling sequence of a given terminalcolliding with the scrambling sequence of any remaining terminal is10⁻³. This collision probability may be sufficiently low and may havenegligible impact on system performance.

The use of a dynamic parameter to generate the scrambling sequence mayreduce the likelihood of repeated collisions between the pilots from twoterminals. For example, a first set of static and dynamic parameters fora first terminal may be hashed to the same digest as a second set ofstatic and dynamic parameters for a second terminal, even although thesetwo parameter sets are different, due to the random nature of the hashfunction. The dynamic parameter may be system time, which would changefor each pilot transmission instance, thus ensuring a different set ofparameters input to the hash function. The hash function input thereforechanges from pilot transmission instance to pilot transmission instance,and is further different for different terminals due to the presence ofthe static parameters. As a result, the hash output is different foreach terminal and for each pilot transmission instance, thus reducingthe likelihood of repeated collisions. If the scrambling sequences oftwo terminals collide in one pilot transmission instance, then thesescrambling sequences will likely not collide in the next pilottransmission instance. The likelihood of collision in each pilottransmission instance may be an independent event with a probability of10⁻⁶ due to the use of system time as one of the inputs to the hashfunction.

The hashing also allows for use of a shorter length PN generator for thescrambling sequence, which may simplify implementation. The PN generatormay be initialized with the seed and may then be operated to generatethe scrambling sequence for the pilot.

The pilot from terminal 120 may be used for various purposes. Servingsector 110 may use the pilot as a reference signal to estimate thereceived signal quality for terminal 120. Serving sector 110 maydetermine power control (PC) commands based on the received signalquality and may send the PC commands on a Forward Power Control Channel(F-PCCH) to terminal 120. Terminal 120 may adjust its transmit power ortransmit power density (PSD) based on the PC commands. The pilot fromterminal 120 may thus be used as a reference to set the power levels ofdata and control channels sent by terminal 120.

All sectors in the active set of terminal 120 may receive the pilot fromterminal 120 and determine the strength at which the pilot is received.Each sector in the active set may determine a pilot quality indicator(PQI) based on the received pilot strength and may send the PQI on aForward PQI Channel (F-PQICH) to terminal 120. Terminal 120 may use thePQIs from all sectors in the active set to determine which sector hasthe best reverse link (e.g., the highest received pilot strength) forterminal 120 and may use this information to make decisions for handoffon the reverse link.

Terminal 120 may also scramble traffic data sent to the serving sectorand may use a scrambling sequence that is specific to the servingsector. In one design, the scrambling sequence for traffic data may begenerated based on a set of parameters given in Table 2.

TABLE 2 Parameters for scrambling sequence for traffic data ParameterLength Description PilotID 10 bits ID of the serving sector for terminal120. MACID 11 bits ID assigned to terminal 120 by the serving sector.System time 10 bits Time at which traffic data is transmitted byterminal 120.

The PilotID and MACID in Table 2 are related to the serving sector andmay be different from the PilotID and MACID in Table 1, which arerelated to the initial access sector. This may be the case if terminal120 has been handed off from the initial accessed sector to the currentserving sector. The system time may be given in various formats. In onedesign, the system time may be given by 4 LSBs of a superframe index anda 6-bit frame index of a frame within a superframe in which traffic datais transmitted.

Table 2 shows an example set of parameters and an example size for eachparameter, in accordance with one specific design. These parameters mayhave other sizes. Other parameters may also be used to generate thescrambling sequence for traffic data. For example, a packet format indexfor a packet may be used as a parameter for the scrambling sequence fortraffic data. Other combinations of parameters may also be used for thescrambling sequence for traffic data.

FIG. 3 shows a block diagram of a design of terminal 120, servingsector/base station 110, and active set sector/base station 112 inFIG. 1. At terminal 120, a transmit processor 320 may receive trafficdata from a data source 312 and signaling from a controller/processor330. Transmit processor 320 may process (e.g., encode, interleave, andsymbol map) the traffic data, signaling, and pilot and provide datasymbols, signaling symbols, and pilot symbols, respectively. As usedherein, a data symbol is a symbol for traffic data, a signaling symbolis a symbol for signaling or control information, a pilot symbol is asymbol for pilot, and a symbol is typically a complex value. A modulator(MOD) 322 may perform modulation on the data, signaling, and pilotsymbols (e.g., for OFDM) and provide output chips. Each chip may be acomplex value in the time domain. A transmitter (TMTR) 324 may condition(e.g., convert to analog, amplify, filter, and upconvert) the outputchips and generate a reverse link signal, which may be transmitted viaan antenna 326.

At serving sector 110, an antenna 352 a may receive the reverse linksignals from terminal 120 and other terminals. A receiver (RCVR) 354 amay condition (e.g., filter, amplify, downconvert, and digitize) thereceived signal from antenna 352 a and provide samples. A demodulator(DEMOD) 356 a may perform demodulation on the samples (e.g., for OFDM)and provide symbol estimates. A receive processor 360 a may process(e.g., symbol demap, deinterleave, and decode) the symbol estimates,provide decoded data to a data sink 362 a, and provide decoded signalingto a controller/processor 370 a.

Sector 112 may similarly receive and process the reverse link signalsfrom terminal 120 and other terminals. The received signal from anantenna 352 b may be conditioned by a receiver 354 b, demodulated by ademodulator 356 b, and processed by a receive processor 360 b.

On the forward link, a transmit processor 382 a at serving sector 110may receive and process traffic data from a data source 380 a andsignaling (e.g., PC commands, PQIs, etc.) from controller/processor 370a. A modulator 384 a may perform modulation on data, signaling, andpilot symbols from transmit processor 382 a and provide output chips. Atransmitter 386 a may condition the output chips and generate a forwardlink signal, which may be transmitted via antenna 352 a. Sector 112 maysimilarly process and transmit traffic data, signaling, and pilot toterminals within its coverage.

At terminal 120, the forward link signals from sectors 110 and 112 andother sectors may be received by antenna 326, conditioned by a receiver340, demodulated by a demodulator 342, and processed by a receiveprocessor 344. Processor 344 may provide decoded data to a data sink 346and decoded signaling to controller/processor 330.

Controllers/processors 330, 370 a and 370 b may direct the operation atterminal 120 and sectors 110 and 112, respectively. Memories 332, 372 aand 372 b may store data and program codes for terminal 120 and sectors110 and 112, respectively. Schedulers 374 a and 374 b may scheduleterminals communicating with sectors 110 and 112, respectively, and mayassign channels and/or time frequency resources to the terminals.

FIG. 4 shows a block diagram of a design of transmit processor 320 atterminal 120 in FIG. 3. In this design, transmit processor 320 includesa TX pilot processor 410 and a TX data processor 420.

Within TX pilot processor 410, a generator 412 may receive the set ofparameters for the scrambling sequence for the pilot, e.g., theparameters in Table 1. Generator 412 may generate the scramblingsequence for the pilot based on the received set of parameters. Ascrambler 414 may scramble pilot data with the scrambling sequence fromgenerator 412 and provide scrambled pilot data. The pilot data may beany known data, e.g., an orthogonal sequence, a sequence of all ones, aknown PN sequence, etc. A generator 416 may generate pilot symbols basedon the scrambled pilot data and provide the pilot symbols to modulator322.

Within TX data processor 420, a generator 422 may receive the set ofparameters for the scrambling sequence for traffic data, e.g., theparameters in Table 2. Generator 422 may generate the scramblingsequence for traffic data based on the received set of parameters. Anencoder and interleaver 424 may receive and encode a packet of trafficdata to obtain a coded packet and may further interleave the bits in thecoded packet based on an interleaving scheme. A scrambler 426 mayscramble the bits from interleaver 424 to randomize the data. A symbolmapper 428 may map the scrambled traffic data to data symbols based on aselected modulation scheme.

FIG. 5 shows a block diagram of a design of TX pilot processor 410 inFIG. 4. Within scrambling sequence generator 412, a multiplexer (Mux)512 may receive and concatenate the set of parameters for the scramblingsequence for the pilot, e.g., the parameters in Table 1. A hash function514 may receive and hash the concatenated set of parameters and providea hash digest. The hash digest may have a fixed size (e.g., 20 bits) andmay be used as a seed for a PN generator 516. PN generator 516 may beinitialized with the seed and may provide a pseudo-random chip sequenceas the scrambling sequence. Within scrambler 414, a multiplier 522 mayperform chip-by-chip multiply of the pilot data with the scramblingsequence and provide scrambled pilot data. In one design, the pilot datais a sequence of L ones, the scrambling sequence is a pseudo-randomsequence of L chips, and the scrambled pilot data is the pseudo-randomsequence of L chips. The pilot data may also be other orthogonalsequence or other known data.

Within pilot symbol generator 416, a multiplier 532 may scale each chipfrom scrambler 414 with a gain for the R-PICH. An interleaver 534 maypermute the sequence of chips from multiplier 532. In one design, thepilot is transmitted in a CDMA subsegment of M subcarriers in N OFDMsymbol periods, as shown in FIG. 2. A unit 536 may partition the chipsequence from interleaver 534 into N subsequences, with each subsequenceincluding M chips. In each OFDM symbol period of the CDMA subsegment, adiscrete Fourier transform (DFT) unit 538 may perform an M-point DFT onthe M chips in the subsequence for that OFDM symbol period and provide Mpilot symbols for the N subcarriers in the OFDM symbol period.

As noted above, multiple terminals may transmit different channels inthe same CDMA subsegment using CDM. Terminal 120 may send a log₂(L)-bitvalue on a channel in the CDMA subsegment by (i) mapping this value toan L-chip Walsh sequence and (ii) scrambling the L-chip Walsh sequencewith an L-chip scrambling sequence to obtain an L-chip pseudo-randomsequence. This pseudo-random sequence may be superimposed with otherpseudo-random sequences from other terminals and/or other channels inthe CDMA subsegment. This superposition constitutes the CDM.

Scrambling sequence generator 422 and scrambler 426 for TX dataprocessor 420 in FIG. 4 may be implemented in similar manner asscrambling sequence generator 412 and scrambler 414, respectively, inFIG. 5. However, the hash function within scrambling sequence generator422 may generate a seed based on a different set of parameters fortraffic data, e.g., the parameters in Table 2.

A sector may receive pilots from any number of terminals. The sector mayhave the set of parameters for the scrambling sequence for the pilot foreach terminal to be received by the sector. The sector may receive andprocess the pilot sent by each terminal based on the scrambling sequenceused by that terminal for the pilot.

FIG. 6 shows a block diagram of a design of receive processor 360, whichmay be used for receive processors 360 a and 360 b in FIG. 3. Receiveprocessor 360 includes a receive (RX) pilot processor 610 and an RX dataprocessor 630.

Within RX pilot processor 610, a pilot symbol processor 612 may obtainreceived symbols for a CDMA subsegment and may process these receivedsymbols in a manner complementary to the processing by pilot symbolgenerator 416 in FIG. 5. Processor 612 may perform an M-point inverseDFT (IDFT) on M received symbols for each OFDM symbol period to obtain Minput samples. Processor 612 may then assemble the input samples for theN OFDM symbol periods of the CDMA subsegment to obtain a sequence of Linput samples.

A scrambling sequence generator 614 may generate the scrambling sequencefor the pilot for terminal 120 based on the set of parameters used byterminal 120 for the pilot. Generator 614 may be implemented withgenerator 412 in FIG. 5. A descrambler 616 may descramble the sequenceof input samples with the scrambling sequence and provide a descrambledsequence. A pilot correlator 618 may correlate the descrambled sequencewith the pilot data. An energy accumulator 620 may accumulate theenergies of all samples from pilot correlator 618. The pilot fromterminal 120 may be received via one or more signal paths. RX pilotprocessor 610 may perform processing for each signal path of interestand may then combine the energies of all signal paths to obtain thereceived pilot strength for terminal 120. A PQI generator 622 may obtainthe received pilot strength and determine a PQI for terminal 120. Anestimator 624 may estimate the received signal quality for terminal 120.A generator 626 may generate a PC command for terminal 120 based on thereceived signal quality. The PC command and PQI may be sent to terminal120.

RX data processor 630 may process received symbols for traffic data in amanner complementary to the processing by TX data processor 420 in FIG.4. Processor 630 may generate a scrambling sequence for traffic databased on the set of parameters used by terminal 120 for traffic data.Processor 630 may then perform descrambling for traffic data with thisscrambling sequence.

FIG. 7 shows a design of a process 700 for transmitting pilot byterminal 120. A scrambling sequence may be generated based on a set ofparameters comprising at least one static parameter and possibly atleast one dynamic parameter (block 712). The at least one staticparameter has fixed value for an entire communication session for theterminal. The at least one static parameter may be determined duringinitial system access by the terminal and may be independent of theserving sector for the terminal. The at least one static parameter mayinclude at least one of an ID of a sector initially accessed by theterminal, an ID assigned to the terminal by the initial accessed sector,an access sequence index used by the terminal for the initial systemaccess, and time of the initial system access by the terminal. The atleast one dynamic parameter has variable value during the communicationsession and may include a parameter for system time. The parameter forsystem time may include a superframe index for a superframe in which thepilot is sent and/or a frame index for a frame within the superframe inwhich the pilot is sent. For block 712, the set of parameters may behashed to obtain a seed, and the scrambling sequence may be generatedbased on the seed.

A pilot may be generated based on the scrambling sequence (block 714).For block 714, pilot data may be scrambled with the scrambling sequenceto obtain scrambled pilot data. Pilot symbols may be generated based onthe scrambled pilot data and may be mapped to a time frequency blockused to send the pilot. The pilot data may comprise an orthogonalsequence or some other known data. The pilot may comprise the pilotsymbols. The time frequency block may be for a CDMA subsegment used bydifferent terminals to send pilots and/or other information on thereverse link.

The pilot may be sent to at least one sector including the servingsector for the terminal (block 716). The at least one sector may be inan active set of the terminal.

A PC command determined based on the pilot may be received from theserving sector (block 718). Transmit power of the terminal may beadjusted based on the PC command (block 720). A PQI determined based onthe pilot may be received from each of the at least one sector (block722). One of the at least one sector may be selected as the servingsector based on the PQI received from each sector (block 724). Theterminal may be handed off from the serving sector to a new servingsector. The same set of parameters may be used to generate thescrambling sequence for the pilot sent to the new serving sector.

FIG. 8 shows a design of an apparatus 800 for transmitting pilot.Apparatus 800 includes means for generating a scrambling sequence basedon a set of parameters comprising at least one static parameter andpossibly at least one dynamic parameter (module 812), means forgenerating a pilot based on the scrambling sequence (module 814), meansfor sending the pilot to at least one sector including the servingsector for the terminal (module 816), means for receiving a PC commanddetermined based on the pilot from the serving sector (module 818),means for adjusting transmit power of the terminal based on the PCcommand (module 820), means for receiving a PQI determined based on thepilot from each of the at least one sector (module 822), and means forselecting one of the at least one sector as the serving sector based onthe PQI received from each sector (module 824).

FIG. 9 shows a design of a process 900 for receiving pilot by a sector.A pilot may be received from the terminal, e.g., from a time frequencyblock used for sending the pilot on the reverse link (block 912). Ascrambling sequence for the terminal may be generated based on a set ofparameters comprising at least one static parameter and possibly atleast one dynamic parameter (block 914). The set of parameters may behashed to obtain a seed, and the scrambling sequence may be generatedbased on the seed. The received pilot may be descrambled with thescrambling sequence to obtain descrambled pilot for the terminal (block916).

Received pilot strength for the terminal may be determined based on thedescrambled pilot (block 918). A PQI may be generated based on thereceived pilot strength (block 920) and sent to the terminal (block922). If the sector is the serving sector for the terminal, thenreceived signal quality for the terminal may be determined based on thedescrambled pilot (block 924). A PC command may be generated based onthe received signal quality (block 926) and sent to the terminal (block928).

FIG. 10 shows a design of an apparatus 1000 for receiving pilot.Apparatus 1000 includes means for receiving a pilot from the terminal(module 1012), means for generating a scrambling sequence for theterminal based on a set of parameters comprising at least one staticparameter and possibly at least one dynamic parameter (module 1014),means for descrambling the received pilot with the scrambling sequenceto obtain descrambled pilot for the terminal (module 1016), means fordetermining received pilot strength for the terminal based on thedescrambled pilot (module 1018), means for generating a PQI based on thereceived pilot strength (module 1020), means for sending the PQI to theterminal (module 1022), means for determining received signal qualityfor the terminal based on the descrambled pilot (module 1024), means forgenerating a PC command based on the received signal quality (module1026), and means for sending the PC command to the terminal (module1028).

FIG. 11 shows a design of a process 1100 for transmitting pilot andtraffic data by terminal 120. A first scrambling sequence may begenerated based on a first set of parameters (block 1112). The first setof parameters may be hashed to obtain a first seed, and the firstscrambling sequence may be generated based on the first seed. A pilotmay be generated based on the first scrambling sequence (block 1114).The pilot may be sent to at least one sector including the servingsector for the terminal (block 1116).

A second scrambling sequence may be generated based on a second set ofparameters (block 1118). The second set of parameters may be hashed toobtain a second seed, and the second scrambling sequence may begenerated based on the second seed. Traffic data may be scrambled basedon the second scrambling sequence to obtain scrambled traffic data(block 1120). The scrambled traffic data may be sent to the servingsector (block 1122).

The first set may include at least one parameter independent of theserving sector. The first set may include at least one of an ID of asector initially accessed by the terminal, an ID assigned to theterminal by the initial accessed sector, an access sequence index usedby the terminal for initial system access, and time of the initialsystem access by the terminal. The second set may include at least oneparameter dependent on the serving sector. The second set may include atleast one of an ID of the serving sector and an ID assigned to theterminal by the serving sector. The first and second sets may eachinclude a parameter for system time, which may include (i) a superframeindex for a superframe in which pilot or traffic data is sent and/or(ii) a frame index for a frame within the superframe in which the pilotor traffic data is sent. The first and second sets may also includeother parameters.

FIG. 12 shows a design of an apparatus 1200 for transmitting pilot andtraffic data. Apparatus 1200 includes means for generating a firstscrambling sequence based on a first set of parameters (module 1212),means for generating a pilot based on the first scrambling sequence(module 1214), means for sending the pilot to at least one sectorincluding the serving sector for the terminal (module 1216), means forgenerating a second scrambling sequence based on a second set ofparameters (module 1218), means for scrambling traffic data based on thesecond scrambling sequence to obtain scrambled traffic data (module1220), and means for sending the scrambled traffic data to the servingsector (module 1222).

FIG. 13 shows a design of a process 1300 for receiving pilot and trafficdata by a sector. A pilot may be received from the terminal (block1312). A first scrambling sequence may be generated based on a first setof parameters, which may include any of the parameters in Table 1 (block1314). The first set of parameters may be hashed to obtain a first seed,and the first scrambling sequence may be generated based on the firstseed. The received pilot may be descrambled with the first scramblingsequence to obtain descrambled pilot (block 1316).

Traffic data may also be received from the terminal (block 1318). Asecond scrambling sequence may be generated based on a second set ofparameters, which may include any of the parameters in Table 2 (block1320). The second set of parameters may be hashed to obtain a secondseed, and the second scrambling sequence may be generated based on thesecond seed. The received traffic data may be descrambled with thesecond scrambling sequence to obtain descrambled traffic data (block1322).

FIG. 14 shows a design of an apparatus 1400 for receiving pilot andtraffic data. Apparatus 1200 includes means for receiving a pilot from aterminal (module 1412), means for generating a first scrambling sequencebased on a first set of parameters (module 1414), means for descramblingthe received pilot with the first scrambling sequence to obtaindescrambled pilot (module 1416), means for receiving traffic data fromthe terminal (module 1418), means for generating a second scramblingsequence based on a second set of parameters (module 1420), and meansfor descrambling the received traffic data with the second scramblingsequence to obtain descrambled traffic data (module 1422).

The modules in FIGS. 8, 10, 12 and 14 may comprise processors,electronics devices, hardware devices, electronics components, logicalcircuits, memories, etc., or any combination thereof.

The techniques described herein may be implemented by various means. Forexample, these techniques may be implemented in hardware, firmware,software, or a combination thereof. For a hardware implementation, theprocessing units used to perform the techniques at an entity (e.g., aterminal or a base station) may be implemented within one or moreapplication specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, micro-controllers, microprocessors,electronic devices, other electronic units designed to perform thefunctions described herein, a computer, or a combination thereof.

For a firmware and/or software implementation, the techniques may beimplemented with code (e.g., procedures, functions, modules,instructions, etc.) that performs the functions described herein. Ingeneral, any computer/processor-readable medium tangibly embodyingfirmware and/or software code may be used in implementing the techniquesdescribed herein. For example, the firmware and/or software code may bestored in a memory (e.g., memory 332, 372 a or 372 b in FIG. 3) andexecuted by a processor (e.g., processor 330, 370 a or 370 b). Thememory may be implemented within the processor or external to theprocessor. The firmware and/or software code may also be stored in acomputer/processor-readable medium such as random access memory (RAM),read-only memory (ROM), non-volatile random access memory (NVRAM),programmable read-only memory (PROM), electrically erasable PROM(EEPROM), FLASH memory, floppy disk, compact disc (CD), digitalversatile disc (DVD), magnetic or optical data storage device, etc. Thecode may be executable by one or more computers/processors and may causethe computer/processor(s) to perform certain aspects of thefunctionality described herein.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

1. An apparatus for wireless communication, comprising: at least oneprocessor configured to generate a scrambling sequence based on a set ofparameters comprising at least one static parameter, to generate a pilotbased on the scrambling sequence, and to send the pilot from a terminalto at least one sector; and a memory coupled to the at least oneprocessor.
 2. The apparatus of claim 1, wherein the at least oneprocessor is configured to hash the set of parameters to obtain a seedand to generate the scrambling sequence based on the seed.
 3. Theapparatus of claim 1, wherein the at least one processor is configuredto scramble pilot data with the scrambling sequence to obtain scrambledpilot data, to generate pilot symbols based on the scrambled pilot data,and to map the pilot symbols to a time frequency block used to send thepilot.
 4. The apparatus of claim 3, wherein the pilot data comprises asequence of all ones.
 5. The apparatus of claim 1, wherein the at leastone processor is configured to generate the pilot based further on pilotdata comprising an orthogonal sequence, and to send the pilot in a timefrequency block for a Code Division Multiple Access (CDMA) subsegmentused by multiple terminals to send pilots on reverse link.
 6. Theapparatus of claim 1, wherein the at least one static parameter hasfixed value for an entire communication session for the terminal.
 7. Theapparatus of claim 1, wherein the at least one static parameter isindependent of a serving sector for the terminal.
 8. The apparatus ofclaim 1, wherein the at least one processor is configured to obtain theat least one static parameter after completing initial system access bythe terminal.
 9. The apparatus of claim 1, wherein the at least onestatic parameter comprises at least one of an identifier (ID) of asector initially accessed by the terminal, an ID assigned to theterminal by the initial accessed sector, an access sequence index usedby the terminal for initial system access, and time of the initialsystem access by the terminal.
 10. The apparatus of claim 1, wherein theset of parameters further comprises at least one dynamic parameterhaving variable value during a communication session for the terminal.11. The apparatus of claim 10, wherein the at least one dynamicparameter comprises a parameter for system time.
 12. The apparatus ofclaim 11, wherein the parameter for system time comprises a superframeindex for a superframe in which the pilot is sent.
 13. The apparatus ofclaim 12, wherein the parameter for system time further comprises aframe index for a frame within the superframe in which the pilot issent.
 14. The apparatus of claim 1, wherein the at least one processoris configured to receive a power control (PC) command from a servingsector for the terminal, the PC command being determined based on thepilot, and to adjust transmit power based on the PC command.
 15. Theapparatus of claim 1, wherein the at least one processor is configuredto receive a pilot quality indicator (PQI) from each of the at least onesector, the PQI from each sector being determined based on the pilot,and to select one of the at least one sector as a serving sector for theterminal based on the PQI received from each of the at least one sector.16. The apparatus of claim 1, wherein the at least one processor isconfigured to perform handoff from a current serving sector to a newserving sector, and to use the set of parameters to generate thescrambling sequence for pilot sent to the new serving sector.
 17. Amethod for wireless communication, comprising: generating a scramblingsequence based on a set of parameters comprising at least one staticparameter; generating a pilot based on the scrambling sequence; andsending the pilot from a terminal to at least one sector.
 18. The methodof claim 17, wherein the generating the scrambling sequence compriseshashing the set of parameters to obtain a seed, and generating thescrambling sequence based on the seed.
 19. The method of claim 17,wherein the set of parameters further comprises at least one dynamicparameter, the at least one static parameter having fixed value for anentire communication session for the terminal, the at least one dynamicparameter having variable value during the communication session. 20.The method of claim 19, wherein the at least one dynamic parametercomprises a parameter for system time.
 21. An apparatus for wirelesscommunication, comprising: means for generating a scrambling sequencebased on a set of parameters comprising at least one static parameter;means for generating a pilot based on the scrambling sequence; and meansfor sending the pilot from a terminal to at least one sector.
 22. Theapparatus of claim 21, wherein the set of parameters further comprisesat least one dynamic parameter, the at least one static parameter havingfixed value for an entire communication session for the terminal, andthe at least one dynamic parameter having variable value during thecommunication session.
 23. The apparatus of claim 21, wherein the meansfor generating the scrambling sequence comprises means for hashing theset of parameters to obtain a seed, and means for generating thescrambling sequence based on the seed.
 24. A computer program product,comprising: a computer-readable medium comprising: code for causing atleast one computer to generate a scrambling sequence based on a set ofparameters comprising at least one static parameter; code for causingthe at least one computer to generate a pilot based on the scramblingsequence; and code for causing the at least one computer to send thepilot to at least one sector.
 25. An apparatus for wirelesscommunication, comprising: at least one processor configured to receivea pilot from a terminal, to generate a scrambling sequence for theterminal based on a set of parameters comprising at least one staticparameter, and to descramble the received pilot with the scramblingsequence to obtain descrambled pilot for the terminal; and a memorycoupled to the at least one processor.
 26. The apparatus of claim 25,wherein the at least one processor is configured to hash the set ofparameters to obtain a seed and to generate the scrambling sequencebased on the seed.
 27. The apparatus of claim 25, wherein the set ofparameters further comprises a dynamic parameter for system time. 28.The apparatus of claim 25, wherein the at least one static parametercomprises at least one of an identifier (ID) of a sector initiallyaccessed by the terminal, an ID assigned to the terminal by the initialaccessed sector, an access sequence index used by the terminal forinitial system access, and time of the initial system access by theterminal.
 29. The apparatus of claim 25, wherein the at least oneprocessor is configured to determine received pilot strength for theterminal based on the descrambled pilot, to generate a pilot qualityindicator (PQI) based on the received pilot strength, and to send thePQI to the terminal.
 30. The apparatus of claim 25, wherein the at leastone processor is configured to determine received signal quality for theterminal based on the descrambled pilot, to generate a power control(PC) command based on the received signal quality, and to send the PCcommand to the terminal.
 31. A method for wireless communication,comprising: receiving a pilot from a terminal; generating a scramblingsequence for the terminal based on a set of parameters comprising atleast one static parameter; and descrambling the received pilot with thescrambling sequence to obtain descrambled pilot for the terminal. 32.The method of claim 31, wherein the generating the scrambling sequencecomprises hashing the set of parameters to obtain a seed, and generatingthe scrambling sequence based on the seed.
 33. The method of claim 31,wherein the set of parameters further comprises a dynamic parameter forsystem time.
 34. An apparatus for wireless communication, comprising: atleast one processor configured to generate a first scrambling sequencebased on a first set of parameters, to generate a pilot based on thefirst scrambling sequence, to send the pilot to at least one sectorincluding a serving sector for a terminal, to generate a secondscrambling sequence based on a second set of parameters, to scrambletraffic data based on the second scrambling sequence to obtain scrambledtraffic data, and to send the scrambled traffic data to the servingsector; and a memory coupled to the at least one processor.
 35. Theapparatus of claim 34, wherein the at least one processor is configuredto hash the first set of parameters to obtain a first seed, to generatethe first scrambling sequence based on the first seed, to hash thesecond set of parameters to obtain a second seed, and to generate thesecond scrambling sequence based on the second seed.
 36. The apparatusof claim 34, wherein the first set comprises at least one parameterindependent of the serving sector, and wherein the second set comprisesat least one parameter dependent on the serving sector.
 37. Theapparatus of claim 34, wherein at least one of the first and second setscomprise a parameter for system time.
 38. The apparatus of claim 37,wherein the parameter for system time comprises at least one of asuperframe index for a superframe in which pilot or traffic data is sentand a frame index for a frame within the superframe in which the pilotor traffic data is sent.
 39. The apparatus of claim 34, wherein thefirst set of parameters comprises at least one of an identifier (ID) ofa sector initially accessed by the terminal, an ID assigned to theterminal by the initial accessed sector, an access sequence index usedby the terminal for initial system access, and time of the initialsystem access by the terminal.
 40. The apparatus of claim 34, whereinthe second set of parameters comprises at least one of an identifier(ID) of the serving sector and an ID assigned to the terminal by theserving sector.
 41. A method for wireless communication, comprising:generating a first scrambling sequence based on a first set ofparameters; generating a pilot based on the first scrambling sequence;sending the pilot to at least one sector including a serving sector fora terminal; generating a second scrambling sequence based on a secondset of parameters; scrambling traffic data based on the secondscrambling sequence to obtain scrambled traffic data; and sending thescrambled traffic data to the serving sector.
 42. The method of claim41, wherein the generating the first scrambling sequence compriseshashing the first set of parameters to obtain a first seed, andgenerating the first scrambling sequence based on the first seed, andwherein the generating the second scrambling sequence comprises hashingthe second set of parameters to obtain a second seed, and generating thesecond scrambling sequence based on the second seed.
 43. The method ofclaim 41, wherein at least one of the first and second sets comprise aparameter for system time.
 44. An apparatus for wireless communication,comprising: at least one processor configured to receive a pilot from aterminal, to generate a first scrambling sequence based on a first setof parameters, to descramble the received pilot with the firstscrambling sequence to obtain descrambled pilot, to receive traffic datafrom the terminal, to generate a second scrambling sequence based on asecond set of parameters, and to descramble the received traffic datawith the second scrambling sequence to obtain descrambled traffic data;and a memory coupled to the at least one processor.
 45. The apparatus ofclaim 44, wherein the at least one processor is configured to hash thefirst set of parameters to obtain a first seed, to generate the firstscrambling sequence based on the first seed, to hash the second set ofparameters to obtain a second seed, and to generate the secondscrambling sequence based on the second seed.
 46. The apparatus of claim44, wherein the first set comprises at least one parameter independentof a serving sector for the terminal, and wherein the second setcomprises at least one parameter dependent on the serving sector. 47.The apparatus of claim 44, wherein the first and second sets eachcomprise a parameter for system time.
 48. A method for wirelesscommunication, comprising: receiving a pilot from a terminal; generatinga first scrambling sequence based on a first set of parameters;descrambling the received pilot with the first scrambling sequence toobtain descrambled pilot; receiving traffic data from the terminal;generating a second scrambling sequence based on a second set ofparameters; and descrambling the received traffic data with the secondscrambling sequence to obtain descrambled traffic data.
 49. The methodof claim 48, wherein the generating the first scrambling sequencecomprises hashing the first set of parameters to obtain a first seed,and generating the first scrambling sequence based on the first seed,and wherein the generating the second scrambling sequence compriseshashing the second set of parameters to obtain a second seed, andgenerating the second scrambling sequence based on the second seed.